Multiple-path amplifiers are amplifiers commonly used in wireless communication systems. One specific type of multiple-path amplifier is a Doherty amplifier in which device's various amplifiers may operate in different classes. Today, Doherty amplifiers are used increasingly in base stations that enable the operation of wireless communications networks. Doherty amplifiers include separate amplification paths—typically a carrier path and a peaking path. The two paths may be configured to operate at different classes. More particularly, the carrier amplification path may typically operate in a class AB mode and the peaking amplification path may be biased such that it operates in a class C mode. This can enable improved power-added efficiency and linearity of the amplifier, as compared to a balanced amplifier, at the power levels commonly encountered in wireless communications applications.
In a Doherty amplifier, as well as other types of multiple-path amplifiers, the signals carried on the different paths of the amplifier may be, to some degree, inductively coupled to one another. As a result, signals propagating through one path of the amplifier may be transmitted, via the inductive coupling, into the other paths of the amplifier. This can be detrimental to the amplifier's overall performance, reducing the amplifier's linearity and efficiency.